GpsActionReplay3.3.3.bis (GpsAR) is a software that enables replays and performance analysis from GPS data. It's the old and free version of the software, released first in september 2004 (latest and last in april 2007)
It's a Java application that can be run on any system (including Windows, Linux, Mac), and on any Web browser within an applet (the Java Plug-In must be installed). GpsActionReplay on a Fedora Linux:
The main view provides is a "from the sky" like view: the action is replayed as it was seen from the sky, either from a steady location or following the action. A background map image can be associated to this view. Here are some screenshot and a short animation.
Tips to use and set the main view
Measuring a distance on the screen:
Click and keep on a point of the screen. Keep on pushing the button and drag the mouse to another point. While moving, you see a red colored line between the two points, and the distance is printed. Here on example, we want to know how far are two riders each other. We do the drag action and get the 548 meters distance...
There are several ways to set scale:
Use the scale slider in top of the main interface, as we did for the demo here.
Click on the main screen. This will recenter and Zoom-In. Right-Click, and it will do the opposite (Zoom-out).
Auto rescaling : when the auto-centering on several tracks is choosen, a Zoom-out will be automatically done if necessary so that all mobiles remain visible
Scale button : adapt the scale and the focus so that we view zone exactly fits the selected trajectorie(s). You can choose the relevant tracks in the "trajectories" list (click to choose one, Ctrl-Click to choose several), and then click on the "Scale" button.
Focus can change due to several causes:
Focus by clicking: just click wherever you want on the main view will refocus (and zoom-in) where you clicked. This is possible only if the "auto center" is unchecked
Auto-Center: You can choose one to several trajectories to focus on. Choose the relevant tracks in the "trajectories" list (click to choose one, Ctrl-Click to choose several), and then click on the "CTR" button. The focus will be adjusted dynamically, as if an helicopter would follow the action. It's how we got the first demo of this page.
Four graphs are provided and give animated data through time. They come in a similar visualizer that scrolls the data. On the center are the current data of current observed time. In order to best distinguish the current position, the data appering on the left side are in full color, whereas the data appearing on the right side are not filled.
Here is a screenshot of the tachymeter:
Setting the graph's scale
The vertical scale is auto-computed to fit the tracks being showed (here ranging from 0 to about 20 knots).
The horizontal scale is settable. It enables to choose how much data must be shown:
Click : shows a larger part of the tracks
Right Click : shows a shorter part of the traks
You can see the effect of successive clicks on the graphs below. Right-clicks would have the opposite effect:
Introducing the upwind graph
The upwindgraph is quite uncommon compared to others. It's the reason why we explain it here.
This graph behaves like the Altigraph, except that it is concerned with UPWIND data rather than altitude. It's exactly as if we considered that being closer to the wind would be equivalent to being at a higher altitude. Hence, you can observer the upwind and downwind course as if they were respectively climbing and descending a mountain. See below a track and its associated upwind-graph. When the sailboat is at the upwind mark, the graph is at a top of a mountain, and when the sailboat is at the downwind mark, it's the contrary.
The horizontal scale is set to 500 meters. This means that what is shown between two vertical lines corresponds to 500 meters of a track.
The time-based main controller
Contrary to some other softwares, GpsAR chose to use time as main controller. Indeed, it's not that easy to know what pixel corresponds to what part of the track in such a track in this screenshot.
Rather than to click on a part on the track to select it (even if it's possible with the Center button of the mouse), we prefer to use time, since there is no overlaping (time ever goes from past to future).
Control time with the time slider
All views in GpsAR are constantly and instantly adjusted to current time of control. At any moment, you can set this time as you wish just moving the time slider
True timing versus Synchronization
True timing: time begins with the smallest beginning time of all tracks loaded, and ends withs the biggest time of all tracks. If some tracks have overlaping time, you will see moving at the same time on the screen. But if for example a track is from 8:12 am to 9:15 AM, and another one is from 3:50 PM to 6:46 PM, you will see the first moving, then no one moving, then the second moving. So, it's timing like in real life, for real replays.
Synchronization: time begins at 0:00 for every tracks, and every tracks start moving at the same time. The end's time corresponds to the duration of the longest track. This option is very interesting when you want to compare tracks from different days, or even to compare performance of a same sailor over a same course. Indeed, you can split the track in multiple tracks, each of them being for example one round in an event. Hence, you can see the sailor competiting against himself.
Control time dynamically with the Run bar
You can launch the animation clicking the play button. You can also reverse play with another button. A pause button suspend the animation, and a second push on it resume it (play or reverse play). A stop button stops the animation, and you need to presse play or reverse-play to resume it.
You can directly go to begin or end with two dedicated buttons.
The Auto repeat button in the options' menu enables to choose between stopping the animation when the end is achieved, or continuing animation from begin (or from end when reverse-playing).
Other ways to control time
There are many other ways to control time in GpsAR.
In particular, each time you generate a table, as speed statistics, virtual run, trackpoints data table and so on, clicking on a row will automatically adjust time to the corresponding moment. Hence, all the views focus on the moment corresponding to the data you select in a table.
Another way to set time is to click with center botton of the mouse on a track segment on the main view. The time will be set to the corresponding moment of the middle of this segment. It's handy where there is not a big density of segments where you want to click. Otherwise, it's a mess to select a particular segment!
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